Absolute Death happens to be the Brooklyn extermination service that my wife and I use. But to someone ceaselessly concerned with his health and in the midst of reading about disease, this was a sign from the gods—and not a good one. Hostile forces had recently been gathering at my corporeal borders: moles, lumps, pains. The pen coalesced these into a single, dreadful assault on my well-being. “Our name says it all,” read the tagline on the ominous writing utensil. This was truth in advertising taken to a perverse degree.

Such thinking—restless in the weaving of connections, apocalyptic in its conclusions—is the hypochondriac’s daily routine. It takes no small amount of ingenuity to extrapolate from Have I forgotten my iPhone again? to I must have Alzheimer’s, but we are always ready for disaster, if never quite ready enough. In one clever passage, Belling, a medical historian at Northwestern, compares the condition to a poster for Steven Spielberg’s “Jaws” that shows a woman swimming on the surface of a seemingly bottomless ocean, while a shark rises up towards her from the deep. She is at once unsuspecting and on the point of death. A crucial distinction: what we fear is not the shark itself, but the naïveté with which its prey calmly treads the water.

Hypochondria is an obsession with what lurks below. The word comes from “hypochondrion,” a term that Hippocrates used to refer to the area under the chondros, or the diaphragm. Later, during the Christian era, when leeches were the vanguard of medicine, it was thought that an excess of black bile caused the ailment. In “The Anatomy of Melancholy,” a famous 1621 chronicle of ills bodily and mental, Robert Burton refers to “hypochondriacal melancholy” as “a disease so grievous, so common, I know not wherein to do a more general service…than to prescribe means how to prevent and cure so universal a malady.”

Whatever service Burton hoped to provide with his book appears to have fallen short. As the Scientific Revolution codified medical knowledge and made it more accessible, it empowered the masses to be more intelligently afraid. It had been easier to suppose that demons were responsible for your illness. Those, at least, you could try to pray away. But what are you to do with errant cells and blocked arteries?

Modern psychology has also struggled to understand hypochondria. “The position of hypochondria is still suspended in darkness,” Freud complained in a 1909 lecture. Hypochondria, for him and the psychoanalysts who followed (including my own), is the product of an ego stuck like a car in the mud, expending its energies uselessly, in self-reinforcing frustration—what Hegel had called earlier the “inability to come out of oneself.”

The imagery of darkness is revealing, though not exactly in the way Freud intended. As children, we know nothing of what is inside, and so we often posit the body’s inaccessibility as a darkness, albeit one that routinely emits farts, tears, and blood. Later, that darkness is filled with guts, and, later yet, the guts become differentiated into organs with the simplistic functions we learn about in seventh-grade biology class: the liver filters, the heart pumps, the spleen, well, surely it does something. Healthy adults trust that organs will continue doing what they should like diligent workers in need of minimal supervision. The system may occasionally sputter, but that is why we have the general practitioner.

The hypochondriac never develops that trust in the body’s efficient functioning. For him, it remains what it was from the start, an unknowable, opaque mess to which he is hopelessly bound, like a travelling partner whom he never asked for and, in fact, would jettison if he only could. The darkness of childhood not only refuses to dissipate but grows fecund with cancers, aneurysms, ulcers, deposits. It becomes the oceanic depths from which the shark hungrily swims towards the surface.

This leads to a state of perpetual bewilderment, one described by the novelist Hilary Mantel as a single unanswerable question: “What in God’s name is going on in there?” The answer, I am afraid—have been afraid, ever since a doctor friend of my parents let me look at his medical books when I was a little boy—is written on that pen.

It doesn’t help that we now live in what Barbara Ehrenreich has denounced as “ribbon culture” in “Bright-sided: How Positive Thinking Is Undermining America,” her book about breast cancer. What started with the red AIDS ribbon, in 1991, as well as a pink one for breast cancer that same year, has evolved into a full spectrum of colors, commemorating everything from autism (multicolored puzzle pieces) to celiac disease (lime green). Alertness campaigns tell us to check suspicious moles and get fibroids removed. Yet we should not, like a Woody Allen character, run to the neurologist after every migraine. Unless, of course, that migraine is accompanied by occluded vision and ringing in the ears. Then you really should see someone.

Allen is, in many ways, the ur-hypochondriac, as he has the quick intelligence sometimes associated with the disease. Those who are curious about their bodies are often curious about other things, too, which is probably why so many artists have been hypochondriacs: the ingenuity of thinking up of new ways to die can be channelled into more productive enterprise. In “The Hypochondriacs: Nine Tormented Lives,” Brian Dillon provides pithy accounts of some of history’s most famous hypos: Charles Darwin, Andy Warhol, James Boswell, Charlotte Brontë and Florence Nightingale. Noting that these extraordinary individuals suffered from a condition that put them in the same league, psychologically, as the supremely effete George Costanza, Dillon writes romantically, though not inaccurately, “Hypochondria…was a kind of calling, almost a vocation, that structured a life, or the productive portion of a life. At once crippled and cosseted by fear, the hypochondriac suffered in order to work, to write or to discover in solitude.” If we are to believe Dillon, hypochondria is the steam that powered the engines of creativity.

I have found hypochondria to be rather dull and time-consuming. Searching online for pictures of enlarged lymph nodes has all the furtive desperation of looking at pornography without any of the gratification. And the eternal watchfulness, the constant inspecting until the skin grows red and the mind weary, drains both time and attention, turning you into a solipsistic bore. Cowards may suffer a thousand deaths before they die; a hypochondriac suffers that many in a single afternoon, and, if you give us the time of day, we will tell you about every single one. We simply cannot help it, unable to extricate ourselves from a bathetic cycle of fear and reassurance. Listen to us, pity us, do not discount what we fear. Please.

As psychology has shifted from Freud to neurons, the practice has sought to make more rigorously scientific its understanding of hypochondria, which now affects perhaps as much as five per cent of the American population and siphons an estimated billions (some put the number at a depressing yet unsurprising twenty billion) annually in unnecessary medical visits. In the upcoming fifth edition of the Diagnostic and Statistical Manual of Mental Disorders, universally used to diagnose mental illness, “hypochondria” will be replaced with “Complex Somatic Symptom Disorder,” so that it can be more easily identified and, presumably, treated with either therapy or medication.

These attempts to rebrand hypochondria as a more respectable ailment, to wrest it away from the histrionic types, are noble but ultimately misguided—no serious hypochondriac will accept new medical terminology with such ease. “The challenge of hypochondriasis,” Belling argues, “the reason it is such a troublesome medical term, is that its meaning is dependent on the concept’s escape from the very disciplines that seek to define it.” That’s not to say that hypochondriacs lack self-awareness; most know that our anxiety is disproportionately great. But we want to be crazy on our own terms, not on the terms of a medical profession that, were it any good, would have already banished all illness and most death, thus obviating the need for our heightened worry.

It took September 11th to allay me, at least temporarily, of my own bodily concerns. I had long been accustomed to vigilance, though mine was always turned inward. But now an outward vigilance was required, too.

Those were good years—the years of color alerts and shoe bombers and fuzzy Osama bin Laden videos. Nothing diverts a hypochondriac like real threats to counter his imagined ones. Of course, our terrorism jitters had a hypochondriacal quality of their own, with all their “see something say something” admonitions. There was the Homeland Security Secretary Tom Ridge, lumbering in front of a podium to announce a new threat to our American body politic and the dour John Ashcroft, the U.S. Attorney General, claiming a victory against some hapless would-be “Islamists” in Peoria we all knew to be insignificant—but from which we could nevertheless gain some measure of relief. That is, until the anxious cycle started all over again, with its quasi-medical lexicon rife with rogue cells and the eradicating forces of good, forever out to curb the metastasizing spread of Al Qaeda.

Nor is it only terrorism that has us on high alert. Whenever I see a bottle that advertises itself as “BPA free,” I wonder about the countless bottles I have pressed to my lips that could make no such claim. Steak is the new cigarette. Sunlight is death. An app measures the radiation emitted by your smartphone, though of course you have to have a smartphone to use it in the first place. Also, I suspect we not heard the last of the avian flu. I think the makers of the recent film “Contagion” would agree.

Hypochondria also has the Internet to thank, as does its sibling paranoia. Some four-fifths of Americans now routinely research their own symptoms online, most of them without bothering to check the credibility of their sources. The Mayo Clinic must thus contend, in the digital sphere, with a blogger who claims that the mumps vaccine is a form of government control. In the end, the majority of patients will be calmed by sound medical counsel, but a recalcitrant few—the cyberchondriacs among us—will not, insisting that our symptoms be checked, refusing to curb our suspicions even after they are.

It’s that refusal to be calmed that constitutes the real sickness. I got so many tests for lymphoma, my blood was put through so many obstacle courses that an exasperated oncologist finally informed me that I was “crazy.” Maybe so. But he was a rotten doctor for failing to find what I was sure ailed me.

It is little wonder, then, that doctors loathe hypochondriacs for undermining the cool rationality of medicine with their own imaginings and asking them the question they loathe most: But how do you know?

This existential unease makes the hypochondriac a modern version of the holy fool, the eternal child who cannot be calmed by the assurances with which others are pacified. And maybe he is right, for is it not really all chaos, both without and within? Do we really know anything? Isn’t truth just a thing that people say? Does not darkness surround us all?

For example, my therapist tells me that to worry unceasingly about getting cancer is as irrational as worrying about getting hit by a bus on Flatbush Avenue. In fact, I am terrified of getting hit by a bus on Flatbush Avenue, and I think he is the madman for being so cavalier on the subject. Has he been out there recently? Belling says that hypochondria is “always ironic,” by which she means that, despite all its convolutions, hypochondria is always right. You will get sick and die. The question is only when and how. The bus is coming.

One of the refreshing qualities of “A Condition of Doubt” is its utter impersonality and lack of prescriptive gospel. Maybe that is because Belling is an academic and her prose has been hammered flat by endless rounds of peer review. Whatever the reason, hers is the first book in hypochondria I have finished—and I have started many.

These generally break down into two categories. The first are efforts at self-help, like Dr. Frederic Neuman’s “Worried Sick” and Gordon Asmundson’s “It’s Not All In Your Head,” and though these are well-meaning, they are essentially hopeless. After all, as Belling notes, the hypochondriac’s greatest folly is that he is constantly misreading the signs of his own body. Reading is his curse. To hope to cure him with a book, then, is like hoping to cure a gin-sodden alcoholic with whiskey.

The other category is the memoir, which almost universally treats hypochondria with a jokey remove, as if slightly embarrassed to be talking about the condition. Books like “The Hypochondriac’s Guide to Life. And Death.” by Washington Post columnist Gene Weingarten, Jennifer Traig’s “Well Enough Alone,” and John O’Connell’s “I Told You I Was Ill” don’t quite know whether to be funny or serious, and end up being neither. This is highly unsatisfying, to read a memoir that lacks the conviction of its own anxieties. The humor is just a pose. If you were scared shitless, have the courage to write it that way.

What Belling lacks in humor, she makes up for in irony. She opens her book with an account of Molière’s play “La Malade Imaginaire,” often translated as “The Hypochondriac,” whose protagonist Argan is comically, eternally afraid that he is ill.

Molière played the lead himself. During a performance on the night of February 17, 1673, in the final act, Molière was seized by a paroxysm of coughing and collapsed on stage. The audience laughed, thinking that Argan was up to his old tricks. The laughter, though, was misplaced. Molière, who was suffering from tuberculosis, died that night.

This is the whole conundrum of hypochondria. Sometimes you are just worried, and sometimes you are really sick. You are sometimes Molière, sometimes Argan. A pen is just a pen. Except when it is more than that.

Alexander Nazaryan is on the editorial board of the New York Daily News and is the editor of Page Views, its literary blog. He has just completed his first novel.